Pure DMSO Research Articles

Polyacrylonitrile-DMSO-AgClO 4 solid polymer electrolyte

This paper reports on the preparation and properties of a new type of thin-film, polymer-solvent-salt solid electrolyte, based on polyacrylonitrile (PAN)-dimethyl sulfoxide (DMSO; 30–80 wt.%)-Ag-ClO 4 system that has a high ionic conductivity of 7 × 10 −4Ω −1 cm −1 at room temperature. A good level of mechanical properties, dimensional stability and high conductivity are reached at the DMSO content of ca 70 wt.%. At lower DMSO content in the solid-electrolyte (<40 wt.% of DMSO) the film is brittle and the conductivity decreases below 10 −4Ω −1 cm −1. The dependence of the logarithm of conductivity on the inverse temperature shows two linear regions with a discontinuity at temperatures of ca. 40–70 °C. The potential of the Ag¦Ag +, PAN, DMSO system was measured vs the Ag¦Ag + couple in pure DMSO. The Nernst equation holds in the Ag + concentration range of 10 −3 −5 × 10 −1 mol kg. The standard potential is + 85 mV vs the standard potential of the Ag¦Ag + couple in DMSO. The analysis of the Tafel plots obtained from the direct-current polarization studies in the cell Ag¦(PAN) n AgClO 4(DMSO) xwt.% gave the exchange current density of j 0 > 5 × 10 −2 mA cm −2 and, therefore, the resistance of the charge transfer reaction at room temperature at the order of kΩ cm 2.

Transport Behaviour of Ions in N,N-Dimethylformamide and Dimethyl Sulfoxide at Different Temperatures. Conductance Studies

Molar conductivities of Bu4NBPh4, Bu4NNO3, LiNO3, NaNO3, KNO3 and AgNO3 have been reported in pure DMF and DMSO in the temperature range from 20 to 45 °C. The conductance data have been analyzed in terms of limiting molar conductivity Λ0 and ion-association constant KA. Separation of Λ0 into ionic components Λi 0 has been carried out on the basis of Bu4NBPh4 assumption in order to calculate the effective ionic radii ri in DMF and DMSO. Examination of ri values of K+ and Ag+ ions as a function of temperature revealed some specific interactions of Ag+ ion with DMF and DMSO. In DMSO electrostatic ion-dipole interaction of Li+, Na+ and K+ ions is found to be somewhat modified due to dipole-dipole interaction.

Viscosity Studies of Some Electrolytes in Dimethyl Sulfoxide and N,N-Dimethylformamide at Different Temperatures

The limiting molar conductivity Λ0 and the Jones-Dole viscosity coefficients A and B were measured for Ph4PBPh4, Bu4NBPh4, Bu4NClO4, Ph4PBr, Bu4NBr, NaBPh4, NaClO4, KClO4, LiClO4 and AgClO4 in pure DMF and DMSO at 20, 30 and 40 °C. The experimental coefficients A are compared with the coefficients A calculated from the Falkenhagen-Vernon equation. The ionic viscosity coefficients B, which were obtained using Ph4PBPh4 as the reference electrolyte, are discussed in terms of the contributions in the expression: Bion = Bw + Bsolv + Bord + Bdisord + Bshape.

Separation of Pd2+ from Metal Ions: Cation Chromatography on Stannic Phosphate and Stannic Arsenate Impregnated Papers

The chromatographic behavior of 51 cations on stannic phosphate and stannic arsenate impregnated papers is studied in pure DMSO, 85% formic acid, and DMSO-85% formic acid in the ratios 9:1, 7:3, 5:5, 3:7, and 1:9. It is found that for K+, Rb+, and Cs+ the following equation is true: Rf = a + bC1/2 where C is the formic acid concentration. DMSO + 85% formic acid (7:3) is almost specific for Be2+ and can separate it from Mg2+, Sr2+, Ca2+, and Ba2+. A large number of binary and ternary separations are achieved. Pd2+ is quantitatively separated in 100-µg quantities from binary mixtures as well as from synthetic mixtures containing some interfering ions.

Basicity, nucleophilicity, and nucleofugality in the elimination–substitution reactions of β-phenylmercaptoethyl phenolates in DMSO–ethanol media

Kinetic studies have been performed on the base-promoted 1,2-elmination reactions of a series of β-phenylmercaptoethyl phenolates with potassium ethoxide in EtOH–DMSO media, yielding phenyl vinyl sulfide. The E2 mechanism was indicated by the absence of H/D exchange in the substrate when the reaction in EtOD–DMSO-d6 containing EtO− was carried to partial completion. The Brønsted coefficient values (βLG, effect of nucleofugality on reaction rate) of ca• 0.30 and ca• 0.98 were estimated for the reaction in pure DMSO and ethanol, respectively. Comparison of the results with reported reactions of substrates of similar structure revealed the important role of the phenyl group on sulfur, the leaving-group nucleofugality, and the medium basicity, in controlling the reaction pathways (elimination versus substitution).

17O NMR and FT-IR study of the ionization state of peptides in aprotic solvents Application to Leu-enkephalin

The ionization state of Leu-enkephalin in DMSO and MeCN/DMSO (4/1) solution was studied by the combined use of 17O NMR and FT-IR spectroscopy. After lyophilization or an aqueous solution at nearly neutral pH, Leu-enkephalin essentially exists in the uncharged state in MeCN/DMSO (4/1) solution. In pure DMSO, only 40% of the Leu-enkephalin molecules are in the zwitterionic state under the same conditions.

Valinomycin and its interaction with ions in organic solvents, detergents, and lipids studied by Fourier transform IR spectroscopy

The structure of valinomycin in a range of organic solvents of varying polarity and in detergent and lipid dispersions has been studied by Fourier transform ir spectroscopy. In solvents of low polarity such as chloroform, ir spectra of valinomycin are fully consistent with the bracelet structure proposed on the basis of nmr spectroscopy, showing a single narrow amide I component attributable to the presence of beta-turns and a single band arising from nonhydrogen-bonded ester C = O groups. K+ complexation results in a downward shift in the amide I band frequency, indicating an increase in the strength of the amide hydrogen bonds, along with a shift to lower frequencies of the ester C = O absorption due to a reduction in electron density in these bonds upon complexation. Identical results were obtained with NH4+, a finding not previously reported. In solvents of both medium (CHCl3/DMSO 3:1) and high (pure DMSO) polarity, we find evidence of significant disruption of the internal hydrogen-bonding network of the peptide and the appearance of a band suggesting the presence of free amide C = O groups. In such solvents, complexation with K+ and NH4+ was not observed. The structure of valinomycin in detergent micelles resembles that in nonpolar organic solvents. However, changes were found in the amide I and ester carbonyl maxima as 2H2O penetrated the micelle which suggest significant interaction between the solvent and peptide. Complexation with K+ was reduced in cationic detergent micelles as a result of a decrease in the effective K+ concentration due to charge repulsion at the micelle surface.(ABSTRACT TRUNCATED AT 250 WORDS)

Protein separation and purification in neat dimethyl sulfoxide

Pure DMSO (instead of water) is used as the reaction medium for protein separations. It is shown that common extracellular proteins (i) have high solubility in DMSO (1–50 mg/ml), (ii) do not irreversibly inactivate in this solvent, and (iii) can adsorb onto carboxymethyl cellulose in DMSO and be subsequently fully desorbed in this solvent by inorganic salts. Ion-exchange chromatography on this resin in DMSO has been used to purify bovine pancreatic trypsin and to separate it from hen egg-white lysozyme in their mixture. Another approach to protein separation in DMSO, fractional precipitation with ethyl acetate (which does not dissolve proteins), has been verified with a mixture of bovine pancreatic chymotrypsinogen and chicken egg ovalbumin.

Dielectric behaviour of DMSO-water mixtures. A hydrogen-bonding model

Abstract A simple model for a hydrogen-bonded mixture treated in the mean field approximation is used to study the excess dielectric properties of water-DMSO solutions at various compositions. The orientation correlation between neighbouring molecules due to short-range specific interactions are discussed in terms of Kirkwood g factors. These are calculated considering only the dipole-correlating hydrogen bonds between water-water and water-DMSO pairs. The model gives a qualitative agreement with experimental data. Temperature dependence of the static dielectric constant and of Kirkwood g factor for pure water and DMSO is also determined and a very good agreement with experiment is observed.

Thermodynamic properties of (0.32 DMSO-H 2O) mixture and pure DMSO under pressure

The sound velocity under pressure together with thermodynamic quantities at P = 1 atm are used to compute the thermodynamic properties of the (0.32 DMSO-H 2O) mixture up to 500 MPa and the pure DMSO up to 220 MPa. As the density is increased, the mixture behaves like a normal liquid and becomes more ideal.

Base catalyzed proton exchange rates of a model cyclopeptide in water-dimethylsulphoxide solutions

Proton tranfers on the peptide bond of cyclo-Glycyl-L-Prolyl (PH) were studid at 25°C by DNMR in seven H 2O/DMSO mixtures (SH) ranging from pure water to anhydrous DMSO. Two kinetic processes (I) and (II) are observed, catalyzed by the conjugate base of either the solvent (OH-) or of the peptide (P-). Mechanisms (I) and (II) were observed alone in the most or least aqueous solvents, respectively. The rate constant of mechanism I, k I $ ̃ 10 9 M -1s -1 is nearly constant along the series of solvents, being levelled to its diffusion limit. The backward reaction is made slower by addition of DMSO, so that the pK of the peptide (pK NH) becomes smaller than that of the solvent (pK SH) in the least aqueous mixtures, pK NH=18.3 against pK SH=22 to 33. Rate constants for mechanism (II) increase from pure DMSO (1.81×1O 6M -1s -1) to the more aqueous solvents (-5×1O 8M -1s -1 when X DMSO=0.35), mainly because of bridging water molecules transferring protons within the acid-base pair PH/P-through a Grotthus mechanism.

Density, refractive index, viscosity and 1H nuclear magnetic resonance measurements of dimethyl sulphoxide at 2 °C intervals in the range 20–60 °C. Structural implications

The density, refractive index, kinematic viscosity and 400 MHz 1H n.m.r. spectra of pure DMSO have been measured very accurately at two degree intervals in the range 20–60 °C. The measurements were analysed statistically to detect marked changes in these physical properties that might indicate a liquid structural transition temperature previously suggested to occur between 40 and 60 °C. Over the temperature range studied it was found that the measurements of density and refractive index varied linearly with temperature, whereas smooth, curved plots were obtained for measurements of kinematic viscosity and 1H n.m.r. chemical shifts with temperature. There is no evidence from these results that the intermolecular-association structure of DMSO breaks down over the temperature range studied.

Stability constants of zinc chloride complexes in DMSO-water mixtures

The stability constants of zinc chloride complexes have been determined potentiometrically measuring the zinc ion activity in DMSO-water mixtures between mole ratios 0.21 and 0.99 for DMSO at 25°C and in a 0.5 M ammonium perchlorate ionic medium. The predominant species are ZnCl 2 and and ZnCl 3 −. The values of the log β's are higher in solvent mixtures than those expected from the values measured in pure DMSO and water.

Medium effects in the systems: Cd2+ OR Zn2+ in some water + organic solvent mixtures deduced from equilibrium potentials at amalgam electrodes

The preferential solvation of Cd2+, Zn2+ and Na+ ions in H2O+CH3OH and H2O+DMSO mixtures was studied on base of equilibrium potential measurements. The electrolyte used was 0.1 and 0.9 M NaClO4. The Cic and BBCr reference systems were compared in H2O+DMSO mixtures. The BBCr system seemed to be more satisfactory. From the equilibrium potentials referred to BBCr the values of the transfer energies of Cd2+, Zn2+ and Na+ ions from H2O to DMSO or to CH3OH were estimated. The transfer energies of Zn2+ and Cd2+ ions as functions of xDMSO decreased monotonically indicating the selective solvation by DMSO in the whole composition range. The limiting values of ΔGtr for pure DMSO were −45 kJ mol−1 and −58 kJ mol−1 for Zn2+ and Cd2+ ions, respectively. The effects were small in the case of Na+ ions and no unambiguous conclusions concerning its selective solvation in this system could be drawn. In H2O+CH3OH mixtures the effects of selective solvation were very small for all three cations up to XCH3OH=0.8.

Medium effects in the systems: Cd 2+ or Zn 2+ in some water+organic solvent mixtures deduced from equilibrium potentials at amalgam electrodes

The preferential solvation of Cd 2+, Zn 2+ and Na + ions in H 2O+CH 3OH and H 2O+DMSO mixtures was studied on base of equilibrium potential measurements. The electrolyte used was 0.1 and 0.9 M NaClO 4. The Cic and BBCr reference systems were compared in H 2O+DMSO mixtures. The BBCr system seemed to be more satisfactory. From the equilibrium potentials referred to BBCr the values of the transfer energies of Cd 2+, Zn 2+ and Na + ions from H 2O to DMSO or to CH 3OH were estimated. The transfer energies of Zn 2+ and Cd 2+ ions as functions of x DMSO decreased monotonically indicating the selective solvation by DMSO in the whole composition range. The limiting values of Δ G tr for pure DMSO were −45 kJ mol −1 and −58 kJ mol −1 for Zn 2+ and Cd 2+ ions, respectively. The effects were small in the case of Na + ions and no unambiguous conclusions concerning its selective solvation in this system could be drawn. In H 2O+CH 3OH mixtures the effects of selective solvation were very small for all three cations up to X CH 3OH =0.8.

A systematic study of the chromatographic behavior of 48 metal lons on plain and stannic arsenate impregnated papers in DMSO-HNO3 systems

The chromatographic behaviour of 48 metal ions on plain and stannic arsenate papers has been studied in DMSO/1 mol dm−3 HNO3 in (9∶1), (7∶3), (5∶5), (3∶7), and (1∶9) ratios and DMSO/8 mol dm−3 HNO3 in (7∶3) ratio. It has been found that for K(I), Rb(I), and Cs(T) Rf=KC1/2 where C is the nitric acid concentration. DMSO/8 mol dm−3 HNO3 (7∶3) is almost specific for In(III) and separates In(III) from Ga(III) and Al(III). Even on plain papers pure DMSO is a useful solvent which separates: Ca(II)−Mg(II), Sn(II)−Sb(III), Cd(II)−Zn(II), Mg(II)−Al(III), Be(II)−Mg(II) and TiO2+−VO2. A comparative study has been made of DMSO−HNO3 and butanol-HNO3 systems for K(II), Rb(I) and Cs(I).

Studies on Phenylpyruvic Acid, II. Keto-Enol Equilibrium in Water-Dimethylsulphoxide Mixtures

Abstract A spectroscopic study of the keto-enol equilibrium of phenylpyruvic acid (PPA) was performed in water-dimethylsulphoxide (DMSO) mixtures, throughout the composition range and in an ex­ tended temperature range. The thermodynamic quantities of the tautomerism were also calculated. The high value of enolization entropy in pure DMSO is attributed to hydrogen bonding of PPA to this solvent. The experimental conditions and the optimum composition range of the H2O-DMSO mixtures for PPA analytical determination were determined.

VAPOR PRESSURE OF PURE DMSO AND VAPOR-LIQUID EQUILIBRIA IN DMSO-H&lt;sub&gt;2&lt;/sub&gt;O SYSTEM UNDER ISOBARIC CONDITIONS

The vapor pressures of pure DMSO were measured from 30 to 150°C by ths isoteniscopic method. An empirical equation for P-T correlation is given and molal heats of vaporization are calculated. The vapor-liquid equilibrium compositions and temperatures were determined experimentally under isobaric conditions of 550, 350, and 150 mmHg pressures for DMSO-H2O system. The activity coefficients are correlated to liquid compositions by Chao and Hougen''s equation.

Concerning the ‘Non‐Specific’ Far Infrared Absorption of Polar Liquids

AbstractThe far infrared spectra of dimethyl sulfoxide and several aliphatic nitriles have been studied with a view towards elucidating the mechanism responsible for the intense absorption bands which have been observed in this region. Spectra of pure liquids, solid DMSO, DMSO‐d6, CD3CN, and dilute solutions in non‐polar solvents are presented. The results are discussed in terms of the possible mechanisms proposed for these absorptions.